Reclamation reality check

The artist's rendering of the post-reclamation Rosemont Copper Mine shows a striking difference in landforms between the graded mine-waste pile and the surrounding undisturbed terrain (HCN, 11/22/10). Particularly noticeable is the difference in what geomorphologists call drainage density, or the total length of drainage channels per acre. The unvarying slopes and rock rundowns in the reclaimed waste piles will erode, over time re-creating drainage densities similar to the surrounding terrain. In the process, toxic materials will probably be exposed and washed downstream. The reclaimed waste piles as currently envisioned also offer little diversity in the direction slopes face, leading to a loss of microclimate diversity, and as a result, less diverse and resilient plant cover.

Over the last decade or so, an alternative -- geomorphic reclamation -- has been developed and tested at several large coal mines in New Mexico and elsewhere. The landforms created have proven to be erosion resistant and are ecologically diverse, natural-appearing ridges, hills and drainage systems. All this reduces or removes the need for long-term maintenance and speeds release of the mining company's reclamation bond. Where designed into the reclamation plan at an early stage, they've also proven, in most cases, to cost the same or less than conventional grading.

I won't speak to the other political, social and technical issues involved at the mine; Tony Davis did a fine job of that in his article. I will say, however, that if Rosemont Copper and Augusta Resource Corporation are truly serious about using state-of-the-art reclamation (and in the process limiting society's and their own long-term liability), they would be implementing such an approach.John KretzmannSanta Fe, New Mexico

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Where can we view this artist’s rendition? I think it is important to note that there are many factors which influence the change of a slope over time. The drainage densities we see on a current landscape are the results of the past and do not necessarily foretell the future. Rates of uplift and rainfall are two important macro influences. The material itself and its permeability are also very important as are the composition and structure of the material and what is capping it.